Torque and Turn Control 2
The most general model of torque-turn analysis of a fastener consists of four distinct zones. The first, the run-down prevailing torque zone, is before the fastener head or nut contacts the bearing surface. The second, the alignment or snugging zone, is the area in which the fastener and the joint mating surfaces are drawn into alignment or a “snug” condition. The third is the elastic clamping range zone. Through this region the slope of the torque-angle curve is constant. The fourth, the post-yield zone, is where an
inflection point begins.
